2 Answers
2

"How did I take that picture?" is a question that functions as a complete sentence, whereas "How I took that picture" is an adverbial clause that cannot stand on its own.

So, the statements beginning with "How did I..." are questions aiming to determine the manner in which an action was carried out. The statements beginning with "How I..." are adverbial clauses of manner that can be added on to complete another sentence.

The adverbial clause can very well stand on its own as a title. This TV series obviously comes to mind, but it would also work for a book/chapter, blog/blog entry, photo album/photo caption...
–
RegDwigнt♦Dec 13 '10 at 13:50

I certainly agree that the clause could stand as a title. After all, most titles are not complete sentences but rather phrases and dependent clauses.
–
Jimi OkeDec 13 '10 at 15:39